Sensing device and method of sensing a light by using the same

ABSTRACT

In a sensing device and a method for sending a light by using the same, the sensing device includes: a lower panel; an upper panel facing the lower panel; a liquid crystal layer disposed between the lower panel and the upper panel; an infrared ray sensor formed in at least one of the lower panel and the upper panel; and a visible ray sensor formed in at least one of the lower panel and the upper panel. The sensing device simultaneously includes the infrared ray sensor and the visible ray sensor such that a touch sensing function or an image sensing function having high reliability may be realized.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patent application Ser. No. 12/753,666 filed on Apr. 2, 2010, which claims priority to Korean Patent Application No. 10-2009-0068511 filed in the Korean Intellectual Property Office on Jul. 27, 2009 and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of the prior applications being herein incorporated by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a sensing device and a method for sensing light by using the same. More particularly, the present invention relates to a sensing device for sensing both infrared rays and visible rays, and a method for sensing such rays by using the same.

(b) Description of the Related Art

Currently, various flat panel displays are being developed and used. Among them, a liquid crystal display is widely used as a flat panel display.

Recently, liquid crystal displays that include a sensing device having a touch sensing function or an image sensing function have been actively researched. However, the conventional sensing device typically achieves the sensing function or the image sensing function through physical changes and therefore it is difficult to obtain high reliability with the conventional devices.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

SUMMARY

In one aspect, the sensing device achieves a light sensing function having high reliability.

A method for sensing a light using the same is also provided.

According to one aspect, a sensing device includes: a lower panel; an upper panel facing the lower panel; a liquid crystal layer disposed between the lower panel and the upper panel; an infrared ray sensor formed in at least one of the lower panel and the upper panel; and a visible ray sensor formed in at least one of the lower panel and the upper panel.

The sensing device may further include a pixel transistor disposed in the lower panel. The lower panel may further include a color filter positioned on the pixel transistor.

The lower panel may further include a black matrix between the color filters, and the black matrix may overlap at least one of the infrared ray sensor and the visible ray sensor. The infrared ray sensor and the visible ray sensor may be formed in the upper panel.

In another aspect, a sensing device includes: a lower panel including a lower substrate and a pixel transistor disposed on the lower substrate; a liquid crystal layer disposed on the lower panel; and an upper panel disposed on the liquid crystal layer and including an upper substrate, an infrared ray sensor, a visible ray sensor, and a readout transistor connected to the infrared ray sensor or the visible ray sensor for transmitting a detection signal to a readout line. The lower panel may further include a color filter disposed on the pixel transistor.

The lower panel may further include a black matrix between the color filters, and the black matrix may overlap at least one of the infrared ray sensor and the visible ray sensor. The infrared ray sensor and the visible ray sensor may be disposed under the upper substrate. The infrared ray sensor and the visible ray sensor may be disposed on the upper substrate.

The sensing device may further include a backlight unit including at least one infrared ray emitting member and at least one visible ray emitting member disposed under the lower panel. The infrared ray emitting member and the visible ray emitting member may be light emitting diodes (LED), and the infrared rays and the visible rays respectively emitted from the infrared ray emitting member and the visible ray emitting member may be perpendicularly incident to the lower panel. The visible ray may be white light.

The sensing device may further include a lower polarizer disposed under the lower panel and an upper polarizer disposed on the upper panel. The sensing device may further include a lower IC unit electrically connected to the pixel transistor for driving the lower panel and disposed on the side of the lower panel, and an upper IC unit electrically connected to the infrared ray sensor and the visible ray sensor for driving the upper panel and disposed on the side of the upper panel.

The lower IC unit and the upper IC unit may not overlap each other. The lower IC unit and the upper IC unit may be opposite to each other with respect to the liquid crystal layer.

According to another aspect, a method for sensing light by using the sensing device is provided. In detail, the method includes: providing a sensing device including an infrared ray sensor and a visible ray sensor, and emitting an infrared ray and a visible ray; disposing an object close to the sensing device; and sensing the infrared ray or the visible ray reflected by the object through the infrared ray sensor or the visible ray sensor, thereby obtaining information of the object.

The information obtained by detecting the infrared ray reflected by the object through the infrared ray sensor may be contact information of the object, i.e. information regarding the position on the sensing device where the object has made contact, or come near to, the sensing device. The information obtained by detecting the visible ray reflected by the object through the visible ray sensor may be image information of the object.

For obtaining of the information, the contact position of the object may be recognized by detecting the infrared ray reflected by the object through the infrared ray sensor, and then the gray level of the visible ray that is provided to the contact position of the object is selectively changed, and thus image information of the object is recognized by detecting the visible rays reflected by the object through the visible ray sensor.

Selectively changing the gray level of the visible ray may be to control the gray level of the sensing device. The sensing device may include a lower panel, an upper panel facing the lower panel, and a liquid crystal layer disposed between the lower panel and the upper panel, the infrared ray sensor is formed in at least one of the lower panel and the upper panel, and the visible ray sensor is formed in at least one of the lower panel and the upper panel. The sensing device may further include a pixel transistor positioned in the lower panel.

The infrared ray sensor and the visible ray sensor may be formed in the upper panel. The infrared ray sensor may include a visible ray blocking film, and the visible ray blocking film may reduce the amount of visible rays incident to the infrared ray sensor such that the sensitivity of the infrared ray sensor to infrared rays may be increased. According to an exemplary embodiment of the present invention, when the lower panel includes the pixel transistor, a light sensing element may be disposed in the upper panel such that the wiring of the lower panel may be simple. Accordingly, signal coupling generated in the lower panel may be reduced.

Also, the light sensing element is positioned in the upper panel such that the sensitivity of the light sensing element, which is decreased when the light sensing element is positioned in the lower panel, may be increased. Also, when the light sensing element is formed under the upper substrate included in the upper panel, the light sensing element may be effectively protected from external impact.

Also, the lower IC unit connected to the lower panel and the upper IC unit connected to the upper panel are separated and are overlapped, such that EMI between the IC units may be reduced.

Also, the visible ray blocking film may block the visible rays provided from outside of the sensing device so that the light [sensing] element may sense the infrared ray such that the signal to noise ratio (SNR) may be improved and the sensitivity may be optimized to the infrared ray region.

Also, the infrared ray sensor and the visible ray sensor are used simultaneously, such that the touch sensing by the infrared ray sensor and the image sensing by the visible ray sensor may be simultaneously executed.

Also, the gray level of the visible rays provided to the portion of the sensing device in which contact with the object is detected is changed after the contact portion of the object is recognized through the infrared ray sensor such that the image sensing may be further effectively executed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a sensing device according to an exemplary embodiment;

FIG. 2 is an enlarged view of the “A” portion of FIG. 1;

FIGS. 3 and 4 are enlarged views of the “B” portion of FIG. 1;

FIGS. 5 and 6 are enlarged views of the “C” portion of FIG. 1;

FIG. 7 is a partially cut-away perspective view of the backlight unit shown in FIG. 1;

FIG. 8 is a perspective view of a circuit integrated unit according to the present exemplary embodiment;

FIG. 9 is a perspective view of a sensing device according to an exemplary embodiment;

FIG. 10 is an enlarged view of the “B” portion of FIG. 9;

FIG. 11 is a cross-sectional view of an infrared ray sensor Tr₂ and a readout transistor Tr_(readout) according to another exemplary embodiment;

FIG. 12 is an enlarged view of the “C” portion of FIG. 9;

FIG. 13 is a cross-sectional view of a visible ray sensor Tr₁ and a readout transistor Tr_(readout) according to another exemplary embodiment; and

FIG. 14 is a view for explaining a method for sensing light using a sensing device according to an exemplary embodiment.

<Description of Reference Numerals Indicating Primary Elements in the Drawings> 3: liquid crystal layer 12: lower polarizer 22: upper polarizer 100: lower panel 110: lower substrate 111: visible ray blocking film 124a, 124b, 124c, 124r: gate 140a, 140b, 140c, 140r: gate electrode insulating layer 154a: semiconductor layer 154r: semiconductor layer 154b, 154c: active layer 164a, 164b, 164c, 164r: ohmic contact layer 173a, 173b, 173c, 173r: source 175a, 175b, 175c, 175r: drain electrode electrode 180: passivation layer 190: pixel electrode 193, 194: insulating layer 200: upper panel 210: upper substrate 540a: lower IC unit 540b: upper IC unit 910: backlight unit 911: infrared ray emitting member 912: visible ray emitting member

DETAILED DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of a sensing device and a method for sensing light by using the same will hereinafter be described in detail with reference to the accompanying drawings.

The structural shapes, sizes, ratios, numbers, etc., are schematically illustrated in the accompanying drawings such that they may be altered. The drawings are shown from a particular viewpoint of observation and the direction or location for explaining the drawings may be variously changed depending upon the position of the observer. Even when reference is made to different elements, like reference numerals may be used to designate those elements.

When the terms “include,” “have,” “consist of,” or the like are used, the relevant subject may include other parts unless the term “only” is used to define the contents thereof. When explanation is made using a singular term, it may be interpreted in a plural manner as well as in a singular manner. Even when the numerical values, shapes, size comparisons, positional relations, etc. are not explained with the adverb “about” or “substantially,” they may be so interpreted as to include the common error ranges. Even when the terms “after,” “before,” “and,” “here,” “subsequently,” or the like are introduced, they are not meant to define temporal locations. The terms “the first,” “the second,” etc. are used only for convenience in distinction, selectively, commutatively, or repeatedly, and are not meant to be read in any defined manner. It will be understood that when an element is referred to as being “on,” “over,” “above,” “below,” or “beside” another element, it can be directly on the other element or one or more intervening elements may also be present. When the connective word “or” is used to connect two elements, it indicates the respective elements and a combination thereof, but when the quantifier “any one of” is used, it indicates only the respective element.

FIG. 1 is a perspective view of a sensing device according to an exemplary embodiment. FIG. 2 is an enlarged view of the “A” portion of FIG. 1. FIGS. 3 and 4 are enlarged views of the “B” portion of FIG. 1. FIGS. 5 and 6 are enlarged views of the “C” portion of FIG. 1. FIG. 7 is a partially cut-away perspective view of the backlight unit shown in FIG. 1. FIG. 8 is a perspective view of a circuit integrated unit according to the present exemplary embodiment.

Referring to FIG. 1, a sensing device includes a lower panel 100, a liquid crystal layer 3 disposed on the lower panel 100, and an upper panel 200 disposed on the liquid crystal layer 3.

The lower panel 100 includes a lower substrate 110 and a pixel transistor Tr₁ disposed on the lower substrate 110. Referring to FIG. 2, which is an enlarged view of the portion “A” of FIG. 1 where a pixel transistor Tr₁ is positioned, pixel transistor Tr₁ includes a gate electrode 124 a, a gate insulating layer 140 a disposed on the gate electrode 124 a, a semiconductor layer 154 a overlapping the gate electrode 124 a and disposed on the gate insulating layer 140 a, an ohmic contact layer 164 a disposed on the semiconductor layer 154 a, a source electrode 173 a disposed on the ohmic contact layer 164 a, and a drain electrode 175 a separated from the source electrode 173 a on the ohmic contact layer 164 a.

The lower panel 100 may further include a gate line disposed on the lower substrate 110 and a data line intersecting the gate line. The gate line may be connected to the gate electrode 124 a of the pixel transistor Tr₁. The data line may also be connected to the source electrode 173 a of the pixel transistor Tr₁.

The lower panel 100 may further include, FIG. 1, a passivation layer 180 disposed on the pixel transistor Tr₁, color filters 230 disposed on the passivation layer 180, a black matrix BM disposed between the color filters 230, an insulating layer 193 disposed on the color filter 230, and a pixel electrode 190 disposed on the insulating layer 193. The pixel electrode 190 may be connected to the drain electrode 175 a of the pixel transistor Tr₁ while passing through the insulating layer 193 and the passivation layer 180.

The upper panel 200 includes an upper substrate 210 and light sensing elements Tr₂ and Tr₃. The light sensing element Tr₂ and Tr₃ may include at least one infrared ray sensor Tr₂ and at least one visible ray sensor Tr₃. The infrared ray sensor Tr₂ and the visible ray sensor Tr₃ formed in the upper panel 200 may overlap the black matrix BM of the lower panel 100. That is, the black matrix BM of the lower panel 100 may vertically correspond to the light sensing elements Tr₂ and Tr₃. In such case, the aperture ratio may be improved.

The infrared ray sensor Tr₂ and the visible ray sensor Tr₃ may be arranged in an alternating manner. As another example, the infrared ray sensor Tr₂ and the visible ray sensor Tr₃ may be arranged unsystematically. As another example, the infrared ray sensor Tr₂ and the visible ray sensor Tr₃ may be arranged in a predetermined ratio. In this case, the ratio of the number of infrared ray sensors Tr₂ and the visible ray sensors Tr₃ may be about 1:1, and may be arranged in an alternating manner.

The upper panel 200 may further include a readout line connected to the light sensing elements Tr₂ and Tr₃ and transmitting a signal detected from the light sensing elements Tr₂ and Tr₃ and a readout transistor Tr_(readout) disposed between the light sensing elements Tr₂ and Tr₃. Here, the readout transistor Tr_(readout) may be disposed with the same layer as the light sensing elements Tr₂ and Tr₃ and closely thereto.

The infrared ray sensor Tr₂ and the visible ray sensor Tr₃ may be disposed under the upper substrate 210. FIG. 3 shows an enlarged infrared ray sensor Tr₂ and the readout transistor Tr_(readout) disposed in the “B” portion of FIG. 1. The infrared ray sensor Tr₂ is disposed under the upper substrate 210, and the readout transistor Tr_(readout) that is electrically connected to the infrared ray sensor Tr₂ is disposed within the same layers as the infrared ray sensor Tr₂.

In detail, the infrared ray sensor Tr₂ may include an active layer 154 b, an ohmic contact layer 164 b, a source electrode 173 b, a drain electrode 175 b, a gate insulating layer 140 b, and a gate electrode 124 b.

The active layer 154 b is disposed under the upper substrate 210, and may include at least one material selected from the group including amorphous germanium, amorphous silicon-germanium, and micro-crystalline silicon. The ohmic contact layer 164 b may be disposed under the active layer 154 b. The source electrode 173 b may be disposed under the ohmic contact layer 164 b. The source electrode 173 b may be disposed separately under the drain electrode 175 b and the ohmic contact layer 164 b. The gate insulating layer 140 b may be disposed under the active layer 154 b, the source electrode 173 b, and the drain electrode 175 b. The gate electrode 124 b may overlap the active layer 154 b under the gate insulating layer 140 b.

The infrared ray sensor Tr₂ may further include a visible ray blocking film 111 disposed on the active layer 154 b and overlapping the active layer 154 b. In detail, the visible ray blocking film 111 may be disposed between the upper substrate 210 and the active layer 154 b. Here, an insulating layer 194 that includes an insulating material such as silicon nitride may be disposed between the visible ray blocking film 111 and the active layer 154 b.

The visible ray blocking film 111 may include a material for blocking the visible rays provided from the outside of the sensing device. For example, the visible ray blocking film 111 may include an organic material or amorphous silicon including a black pigment.

The visible ray blocking film 111 blocks visible rays that are incident to the sensing device, thereby improving the signal to noise ratio (SNR). Additionally, the sensitivity of the active layer 154 b including the amorphous silicon-germanium is optimized to the infrared ray region such that the effect of the visible rays on the active layer 154 b is efficiently prevented.

The readout transistor Tr_(readout) may include a semiconductor layer 154 r, an ohmic contact layer 164 r, a source electrode 173 r, a drain electrode 175 r, a gate insulating layer 140 r, and a gate electrode 124 r.

The semiconductor layer 154 r may be disposed under the upper substrate 210. The ohmic contact layer 164 r may be disposed under the semiconductor layer 154 r.

The source electrode 173 r may be disposed under the ohmic contact layer 164 r. The drain electrode 175 r may be disposed under the ohmic contact layer 164 r and separated from the source electrode 173 r. The gate insulating layer 140 r may be disposed under the semiconductor layer 154 r, the source electrode 173 r, and the drain electrode 175 r. The gate electrode 124 r may be disposed under the gate insulating layer 140 r and overlap the semiconductor layer 154 r.

FIG. 4 is an enlarged cross-sectional view of an infrared ray sensor Tr₂ and a readout transistor Tr_(readout) according to another exemplary embodiment. The infrared ray sensor Tr₂ and the readout transistor Tr_(readout) shown in FIG. 4 are substantially the same as those of FIG. 3, except for the positional relationships of the elements, and therefore the same reference numerals are used to refer to the same elements.

Referring to FIG. 4, the infrared ray sensor Tr₂ is disposed under the upper substrate 210. The readout transistor Tr_(readout) that is electrically connected to the infrared ray sensor Tr₂ is disposed within the same layers as the infrared ray sensor Tr₂.

In detail, the infrared ray sensor Tr₂ may include an active layer 154 b, an ohmic contact layer 164 b, a source electrode 173 b, a drain electrode 175 b, a gate insulating layer 140 b, and a gate electrode 124 b.

The source electrode 173 b and the drain electrode 175 b are separated from each other and are disposed under the upper substrate 210. The active layer 154 b overlaps the source electrode 173 b and the drain electrode 175 b, and is disposed under the source electrode 173 b and the drain electrode 175 b. The ohmic contact layer 164 b is disposed between the active layer 154 b and the source electrode 173 b, and the active layer 154 b and the drain electrode 175 b.

The gate insulating layer 140 b may be disposed under the active layer 154 b, the source electrode 173 b, and the drain electrode 175 b. The gate electrode 124 b may be disposed under the gate insulating layer 140 b while overlapping the active layer 154 b.

The infrared ray sensor Tr₂ further includes the visible ray blocking film 111 overlapping the active layer 154 b and disposed on the active layer 154 b. In detail, the visible ray blocking film 111 may be disposed between the upper substrate 210 and the active layer 154 b. Here, an insulating layer 194 that includes an insulating material such as silicon nitride may be disposed between the visible ray blocking film 111 and the active layer 154 b.

The readout transistor Tr_(readout) may include a semiconductor layer 154 r, an ohmic contact layer 164 r, a source electrode 173 r, a drain electrode 175 r, a gate insulating layer 140 r, and a gate electrode 124 r.

The source electrode 173 r and drain electrode 175 r are separated from each other and are disposed under the upper substrate 210. The semiconductor layer 154 r is disposed under the source electrode 173 r and the drain electrode 175 r so that it is overlapped with the source electrode 173 r and the drain electrode 175 r.

The ohmic contact layer 164 r may be disposed between the semiconductor layer 154 r and the source electrode 173 r, and the semiconductor layer 154 r and the drain electrode 175 r. The gate insulating layer 140 r may be disposed under the semiconductor layer 154 r, the source electrode 173 r, and the drain electrode 175 r. The gate electrode 124 r may be disposed under the gate insulating layer 140 r so that it is overlapped with the semiconductor layer 154 r.

Referring to FIG. 5 which shows an enlarged view of the visible ray sensor Tr₃ and the readout transistor Tr_(readout) that are positioned in the “C” portion of FIG. 1, the visible ray sensor Tr₃ is positioned under the upper substrate 210 and the readout transistor Tr_(readout) that is electrically connected to the visible ray sensor Tr₃ is disposed within the same layers as the visible ray sensor Tr₃.

In detail, the visible ray sensor Tr₃ may include an active layer 154 c, an ohmic contact layer 164 c, a source electrode 173 c, a drain electrode 175 c, a gate insulating layer 140 c, and a gate electrode 124 c.

The active layer 154 c is positioned under the upper substrate 210 and may include amorphous silicon. The ohmic contact layer 164 c may be positioned under the active layer 154 c. The source electrode 173 c may be positioned under the ohmic contact layer 164 c. The drain electrode 175 c is separated from the source electrode 173 c and may be positioned under the ohmic contact layer 164 c. The gate insulating layer 140 c may be positioned under the active layer 154 c, the source electrode 173 c, and the drain electrode 175 c. The gate electrode 124 c may be overlapped with the active layer 154 c under the gate insulating layer 140 c. Also, the readout transistor Tr_(readout) is substantially the same as that of FIG. 3 above, such that the description thereof is omitted here.

In structures of the liquid crystal displays, all of the pixel transistors, the light sensing elements, and the readout transistors may be formed in the lower panel, and only a color filter may be formed in the upper panel. In such case, the relationship between the wiring of the lower panel is complicated such that signal coupling may be generated between the neighboring wiring. Also, when the light sensing element is positioned in the lower panel, the sensitivity for light is reduced, which can cause a problem in that the reliability of the sensing function, which senses the light, is low.

However, in the present exemplary embodiment, the light sensing elements Tr₂ and Tr₃ and the readout transistor Tr_(readout) are positioned in the upper panel 200, the pixel transistor Tr₁ is formed in the lower panel 100, and the color filter is formed in the lower panel 100 such that the signal coupling problem generated in the lower panel may be solved. Also, the light sensing elements Tr₂ and Tr₃ are formed in the upper panel 200 such that the sensitivity for the light is increased, and thereby the reliability of the sensing function for sensing the light may be increased.

Also, the touch sensing function is executed through the infrared ray sensor Tr₂ such that the contact information for the object, i.e., the position on the sensing device, may be obtained in a state in which the object is substantially close to the sensing device or does not contact it.

Also, in the present exemplary embodiment, the light sensing elements Tr₂ and Tr₃ and the readout transistor Tr_(readout) are positioned under the upper substrate 210 such that the light sensing elements Tr₂ and Tr₃ and the readout transistor Tr_(readout) may be prevented from being damaged by external impact.

FIG. 6 is an enlarged view of a visible ray sensor Tr₃ and a readout transistor Tr_(readout) according to another exemplary embodiment of the present invention. The infrared ray sensor Tr₂ and the readout transistor Tr_(readout) shown in FIG. 6 are substantially the same as those of FIG. 5, except for the positional relationships of the elements, so that the same reference numerals are used to refer to the same elements.

Referring to FIG. 6, the visible ray sensor Tr₃ may include an active layer 154 c, an ohmic contact layer 164 c, a source electrode 173 c, a drain electrode 175 c, a gate insulating layer 140 c, and a gate electrode 124 c.

The source electrode 173 c and drain electrode 175 c are disposed under the upper substrate 210 and are separated from each other. The active layer 154 c is disposed under the source electrode 173 c and the drain electrode 175 c while overlapping the source electrode 173 c and the drain electrode 175 c. The ohmic contact layer 164 c may be disposed between the active layer 154 c and the source electrode 173 c, and the active layer 154 c and the drain electrode 175 c. The gate insulating layer 140 c may be positioned under the active layer 154 c, the source electrode 173 c, and the drain electrode 175 c. The gate electrode 124 c may be positioned under the gate insulating layer 140 c so that it is overlapped with the active layer 154 c. The readout transistor Tr_(readout) is substantially the same as that of FIG. 4 above, so that the description thereof is omitted here.

The sensing device further includes a lower polarizer 12 disposed under the lower panel 100 and an upper polarizer 22 disposed on the upper panel 200. The intensity of the light provided to the lower panel 100 and the upper panel 200 is controlled by using the polarization characteristics of the lower polarizer 12 and the upper panel 200.

The sensing device may further include a backlight unit 910 disposed under the lower panel 100. FIG. 7 is the partially cut-away perspective view of the backlight unit 910 shown in FIG. 1. Referring to FIG. 7 the backlight unit 910 includes at least one infrared ray emitting member 911 and at least one visible ray emitting member 912. The infrared ray emitting member 911 and the visible ray emitting member 912 may be a point light source such as a light emitting diode (LED). Also, the infrared rays and the visible rays that are emitted from the infrared ray emitting member 911 and the visible ray emitting member 912, respectively, may be perpendicularly incident to the lower panel 100. Here, the visible rays may be white light.

The infrared ray emitting member 911 and the visible ray emitting member 912 may be uniformly distributed on the whole backlight unit 910 to provide the infrared rays and the visible rays to the entirety of the backlight unit 910. As one example, the infrared ray emitting members 911 and the visible ray emitting members 912 may be arranged in an alternating manner. As another example, the infrared ray emitting members 911 and the visible ray emitting members 912 may be unsystematically arranged. As another example, the infrared ray emitting members 911 and the visible ray emitting members 912 may be arranged in a predetermined ratio. In this case, the infrared ray emitting members 911 and the visible ray emitting members 912 may be arranged in an alternating manner and in a ratio of 1:1.

Referring to FIG. 8, the sensing device may further include a lower IC unit 540 a that is electrically connected to the pixel transistor Tr₁ for driving the lower panel 100 and that is positioned on the side of the lower panel 100. The sensing device may further include and an upper IC unit 540 b that is electrically connected to the light sensing elements Tr₂ and Tr₃ for driving the upper panel 200 and that is positioned on the side of the upper panel 200.

Here, the lower IC unit 540 a and the upper IC unit 540 b are positioned so that they are not overlapped with each other. For example, the lower IC unit 540 a and the upper IC unit 540 b may be opposite to each other with respect to the liquid crystal layer 3.

The lower IC unit 540 a is connected to the data line that is connected to the source electrode 173 a of the pixel transistor Tr₁, thereby receiving and transmitting the electric signals with the pixel transistor Tr₁. The upper IC unit 540 b is connected to the data line that is connected to the source electrode 173 b of the infrared ray sensor Tr₂ or the source electrode 173 c of the visible ray sensor Tr₃, thereby receiving and transmitting the electric signals with the infrared ray sensor Tr₂ or the visible ray sensor Tr₃. On the other hand, the upper IC unit 540 b may be connected to the readout line connected to the source electrode 173 r of the readout transistor Tr_(readout), thereby receiving and transmitting the electric signals with the readout transistor Tr_(readout).

In structures of liquid crystal displays, the lower panel may include the pixel transistors, the light sensing elements, and the readout transistors, and the upper panel may only include the color filter. In such case, the wiring relationship of the lower panel is not only complicated, but also the IC units connected to the wiring must be formed on the side portion of the lower panel, and therefore there is a problem in that EMI is generated between the IC units.

However, according to the present exemplary embodiment, the lower panel 100 includes the lower IC unit 540 a by forming the pixel transistor Tr₁, the upper panel 200 includes the upper IC unit 540 b by forming the light sensing elements Tr₂ and Tr₃, the readout transistor Tr_(readout) is separated from the lower IC unit 540 a, and the lower IC unit 540 a does not overlap the upper IC unit 540 b so that the EMI may be minimized.

In the above-described exemplary embodiments, the infrared ray sensor Tr₂ and the visible ray sensor Tr₃ are both formed in the upper panel 200, however the positions of the infrared ray sensor Tr₂ and the visible ray sensor Tr₃ may be variously changed.

That is, the infrared ray sensor Tr₂ may be formed in at least one of the lower panel 100 and the upper panel 200, and the visible ray sensor Tr₃ may also be formed in at least one of the lower panel 100 and the upper panel 200.

As one example, the infrared ray sensor Tr₂ may be formed in the upper panel 200, and the visible ray sensor Tr₃ may be formed in the lower panel 100. As another example, the visible ray sensor Tr₃ may be formed in the upper panel 200, and the infrared ray sensor Tr₂ may be formed in the lower panel 100.

FIG. 9 is a perspective view of a sensing device according to an exemplary embodiment. FIG. 10 is an enlarged view of the “B” portion of FIG. 9. FIG. 12 is an enlarged view of the “C” portion of FIG. 9.

The present exemplary embodiment is the same as that of the exemplary embodiments shown in FIGS. 1 to 6 except for the structure of the light sensing elements Tr₂ and Tr₃ and the readout transistor Tr_(readout) such that the overlapping description is omitted. Here, the light sensing elements Tr₂ and Tr₃ and the readout transistor Tr_(readout) may be positioned between the upper substrate 210 and the upper polarizer 22.

Referring to FIG. 10, which is an enlarged view of an infrared ray sensor Tr₂ and a readout transistor Tr_(readout) positioned in the “B” portion of FIG. 9, the infrared ray sensor Tr₂ and the readout transistor Tr_(readout) that is electrically connected to the infrared ray sensor Tr₂ are disposed on the upper substrate 210.

In detail, the infrared ray sensor Tr₂ may include a gate electrode 124 b on the upper substrate 210, a gate insulating layer 140 b on the gate electrode 124 b, an active layer 154 b overlapping the gate electrode 124 b on the gate insulating layer 140 b and including at least one material selected from the group amorphous germanium, amorphous silicon-germanium, and microcrystalline silicon, an ohmic contact layer 164 b on the active layer 154 b, a source electrode 173 b on the ohmic contact layer 164 b, and a drain electrode 175 b that is separated from the source electrode 173 b on the ohmic contact layer 164 b.

The infrared ray sensor Tr₂ may further include a visible ray blocking film 111 disposed on the active layer 154 b and overlapping the active layer 154 b. Since the visible ray blocking film 111 has a function of blocking the visible rays provided from outside of the sensing device, the visible ray blocking film 111 may be positioned either on or over the active layer 154 b. The visible ray blocking film 111 is described with reference to FIG. 3 above so that a detailed description thereof will be omitted here. An insulating layer 194 that includes insulating material such as silicon nitride may be positioned between the visible ray blocking film 111 and the active layer 154 b to provide electrical insulation between the visible ray blocking film 194 and the active layer 154 b.

The readout transistor Tr_(readout) may include a gate electrode 124 r on the upper substrate 210, a gate insulating layer 140 r on the gate electrode 124 r, a semiconductor layer 154 r overlapping the gate electrode 124 r on the gate insulating layer 140 r, an ohmic contact layer 164 r on the semiconductor layer 154 r, a source electrode 173 r on the ohmic contact layer 164 r, and a drain electrode 175 r separated from the source electrode 173 r on the ohmic contact layer 164 r.

FIG. 11 is a cross-sectional view of an infrared ray sensor Tr₂ and a readout transistor Tr_(readout) according to another exemplary embodiment. The infrared ray sensor Tr₂ and the readout transistor Tr_(readout) of FIG. 11 are substantially the same as those of FIG. 10, except for the positional relationship of the elements, and therefore the same reference numerals are used to refer to the same elements.

Referring to FIG. 11, an infrared ray sensor Tr₂ and a readout transistor Tr_(readout) that is electrically connected to the infrared ray sensor Tr₂ are disposed on the upper substrate 210.

The infrared ray sensor Tr₂ includes a gate electrode 124 b on the upper substrate 210, a gate insulating layer 140 b on the gate electrode 124 b, a source electrode 173 b and a drain electrode 175 b that are separated from each other and are on the gate insulating layer 140 b, an active layer 154 b overlapping the gate electrode 124 b on the source electrode 173 b and the drain electrode 175 b, and an ohmic contact layer 164 b between the source electrode 173 b and the active layer 154 b, and the drain electrode 175 b and the active layer 154 b.

Also, the infrared ray sensor Tr₂ may further include a visible ray blocking film 111 overlapping the active layer 154 b and disposed on the active layer 154 b. Since the visible ray blocking film 111 has the function of blocking the visible rays provided from outside of the sensing device, the visible ray blocking film 111 may be positioned either on or over the active layer 154 b. The visible ray blocking film 111 is described with reference to FIG. 3 above and therefore a detailed description thereof will be omitted here. An insulating layer 194 that includes insulating material such as silicon nitride may be positioned between the visible ray blocking film 111 and the active layer 154 b to provide electrical insulation between the visible ray blocking film 194 and the active layer 154 b.

The readout transistor Tr_(readout) may include a gate electrode 124 r on the upper substrate 210, a gate insulating layer 140 r on the gate electrode 124 r, a source electrode 173 r and a drain electrode 175 r that are separated from each other and are on the gate insulating layer 140 r, a semiconductor layer 154 r overlapping the gate electrode 12 on the source electrode 173 r and the drain electrode 175 r, and an ohmic contact layer 164 r between the source electrode 173 r and the semiconductor layer 154 r, and the drain electrode 175 r and the semiconductor layer 154 r.

FIG. 12 shows an enlarged view of a visible ray sensor Tr₃ and a readout transistor Tr_(readout) disposed in the “C” portion of FIG. 9. Referring to FIG. 12, the visible ray sensor Tr₃ and the readout transistor Tr_(readout) that is electrically connected to the visible ray sensor Tr₃ are disposed on the upper substrate 210.

In detail, the visible ray sensor Tr₃ may include a gate electrode 124 c on the upper substrate 210, a gate insulating layer 140 c on the gate electrode 124 c, an active layer 154 c that includes amorphous silicon and overlapps the gate electrode 124 c on the gate insulating layer 140 c, an ohmic contact layer 164 c on the active layer 154 c, a source electrode 173 c on the ohmic contact layer 164 c, and a drain electrode 175 c separated from the source electrode 173 c on the ohmic contact layer 164 c. The structure of the readout transistor Tr_(readout) is substantially the same as that of FIG. 10 above, and therefore a detailed description thereof will be omitted here.

FIG. 13 is a cross-sectional view of a visible ray sensor Tr₃ and a readout transistor Tr_(readout) according to another exemplary embodiment. The visible ray sensor Tr₃ and the readout transistor Tr_(readout) of FIG. 13 are substantially the same as those of FIG. 12, except for the positional relationship of the elements, such that the same reference numerals are used to refer to the same elements.

Referring to FIG. 13, the visible ray sensor Tr₃ and the readout transistor Tr_(readout) that is electrically connected to the visible ray sensor Tr₃ are disposed on the upper substrate 210.

The visible ray sensor Tr₃ includes a gate electrode 124 c on the upper substrate 210, a gate insulating layer 140 c on the gate electrode 124 c, a source electrode 173 c and a drain electrode 175 c separated from each other on the gate insulating layer 140 c, an active layer 154 c overlapping the gate electrode 124 c on the source electrode 173 c and the drain electrode 175 c, and an ohmic contact layer 164 c disposed between the source electrode 173 c and the active layer 154 c, and the drain electrode 175 c and the active layer 154 c. The structure of the readout transistor Tr_(readout) is substantially the same as that of FIG. 12 above, and therefore a detailed description thereof will be omitted here.

FIG. 14 is a view for explaining a method for sensing light using a sensing device according to an exemplary embodiment. The method for sensing light according to the present exemplary embodiment is described through the above-described light sensing display device of FIGS. 1 to 6, however the above-described light sensing display device of FIGS. 9 to 13 may be used.

Referring to FIG. 14, the infrared ray and the visible ray are generated from the backlight unit 910. The infrared ray sequentially passes the lower polarizer 12, the lower panel 100, the liquid crystal layer 3, the upper panel 200, and the upper polarizer 22. Also, the visible ray sequentially passes the lower polarizer 12, the lower panel 100, the liquid crystal layer 3, the upper panel 200, and the upper polarizer 22.

For the touch sensing of the first object T₁ positioned on the sensing device, the infrared ray provided from the backlight unit 910 may be used. In detail, when the first object T₁ is close to the sensing device, the infrared ray emitted from the sensing device is reflected by the first object T₁.

Next, the reflected infrared ray is incident to and detected by the infrared ray sensor Tr₂ positioned in the upper panel 200. Accordingly, the touch sensing for the first object T₁ is executed, thereby indicating the contact of the first object T₁, the position of the contact, and the information regarding the shape and the size of the contact.

Thus, for a sensing device that operates using only visible light, when, for instance, the external light is not sufficiently bright, or if, for instance, an insufficient amount of light emitted from such a sensing device arrives at the sensor, due, for instance, to a screen that is in a low gray level configuration, the sensing device may fail to detect the existence of the object. Such a problem may be solved by using infrared rays.

When using infrared rays, the infrared rays are passed through the dark screen that the visible ray cannot pass through in the sensing device such that the infrared rays are reflected, thereby detecting the object via the infrared ray sensor, and as a result the existence, the position, and the shape of the object may be easily recognized. Additional, detection of the object does not require a physical change in the sensing device, and therefore a high reliability may be obtained using infrared rays.

When the gray level of the visible rays emitted from the sensing device is brighter than the luminance of the visible rays incident to the sensing device from outside of the device, the visible rays emitted from the sensing device may be used for image sensing for the second object T₂, when it moves close to the sensing device.

In this case, even if the sensing device is placed in a dark area, without sufficient ambient light, image sensing may be achieved by using the visible rays that are emitted from the sensing device itself.

In detail, the visible rays emitted from the sensing device are reflected by the second object T₂. The reflected visible rays are incident to and detected by the visible ray sensor Tr₁ positioned in the upper panel 200. Accordingly, image sensing for the second object T₂ is executed, and thereby the image information for the second object T₂, such as the shape, the size, and the color, may be obtained.

After confirming the contact of the second object T₂ through the touch sensing, the gray level of the visible rays emitted from the sensing device toward the contact may be selectively changed such that the image sensing for the second object T₂ may be further effectively executed.

For example, when the gray level of the visible rays emitted from the sensing device is darker than the gray level of the visible rays incident to the sensing device from outside of the sensing device, the touch sensing using the infrared ray is executed first. The gray level of the visible rays emitted from the sensing device toward the contact portion of the second object T₂ recognized through the touch sensing is then selectively brightened, so that effective image sensing for the second object T₂ is possible.

That is, when the existence of the object is recognized using the infrared rays, although the screen is dark overall, the portion of the screen where the object is identified as positioned is then displayed with a special gray level such that the image, including the shape of the object, may be recognized, and thereby the more complicated information may be scanned.

Also, as shown in FIG. 3 above, the visible ray blocking film 111 is positioned where the infrared rays and the visible rays are incident upward to the infrared ray sensor Tr₂. By using the visible ray blocking film 111, the visible rays incident to the infrared ray sensor Tr₂ is reduced such that the infrared ray sensitivity of the infrared ray sensor Tr₂ may be increased.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 

What is claimed is:
 1. A sensing device comprising: a lower panel; an upper panel facing the lower panel; and a liquid crystal layer disposed between the lower panel and the upper panel, the upper panel including an upper substrate having a first surface facing a direction where an object to be sensed would be positioned and an opposite surface facing the liquid crystal layer; a plurality of infrared ray sensors disposed in the upper panel on the opposite surface, each infrared ray sensor including a visible ray blocking film contacting the opposite surface, an insulating layer covering and contacting the visible ray blocking film, an active layer disposed on and contacting the insulating layer, a source and drain electrode, each contacting the active layer, the insulating layer and the opposite surface; and a plurality of visible ray sensors disposed in the upper panel on the opposite surface.
 2. The sensing device of claim 1, further comprising a pixel transistor disposed in the lower panel.
 3. The sensing device of claim 2, wherein the lower panel further comprises a color filter positioned on the pixel transistor.
 4. The sensing device of claim 3, wherein the lower panel further includes a black matrix between the color filters, and the black matrix overlaps at least one of the infrared ray sensor and the visible ray sensor.
 5. A sensing device comprising: a lower panel including a lower substrate and a pixel transistor disposed on the lower substrate; a liquid crystal layer disposed on the lower panel; and an upper panel disposed on the liquid crystal layer and including an upper substrate having a first surface facing a direction where an object to be sensed would be positioned and an opposite surface facing the liquid crystal layer, an infrared ray sensor, a visible ray sensor, and a readout transistor connected to the infrared ray sensor or the visible ray sensor for transmitting a detection signal to a readout line, and wherein the infrared ray sensor includes a visible ray blocking film contacting the opposite surface, an insulating layer covering and contacting the visible ray blocking film, an active layer disposed on and contacting the insulating layer, a source and drain electrode, each contacting the active layer, the insulating layer and the opposite surface
 6. The sensing device of claim 5, wherein the lower panel further includes a color filter disposed on the pixel transistor.
 7. The sensing device of claim 6, wherein the lower panel further includes a black matrix between the color filters, and the black matrix overlaps at least one of the infrared ray sensor and the visible ray sensor.
 8. The sensing device of claim 5, further comprising a backlight unit including at least one infrared ray emitting member and at least one visible ray emitting member disposed under the lower panel.
 9. The sensing device of claim 8, wherein the infrared ray emitting member and the visible ray emitting member are light emitting diodes (LED), and infrared rays and visible rays respectively emitted from the infrared ray emitting member and the visible ray emitting member are perpendicularly incident to the lower panel.
 10. The sensing device of claim 9, wherein the visible rays are white light.
 11. The sensing device of claim 5, further comprising: a lower polarizer disposed under the lower panel; and an upper polarizer disposed on the upper panel.
 12. The sensing device of claim 5, further comprising: a lower IC unit electrically connected to the pixel transistor for driving the lower panel, and disposed on a side of the lower panel; and an upper IC unit electrically connected to the infrared ray sensor and the visible ray sensor for driving the upper panel, and disposed on a side of the upper panel.
 13. The sensing device of claim 12, wherein the lower IC unit and the upper IC unit do not overlap each other.
 14. The sensing device of claim 13, wherein the lower IC unit and the upper IC unit are opposite to each other with respect to the liquid crystal layer.
 15. A method for sensing light by using a sensing device, comprising: providing a sensing device including an upper substrate having a first surface facing an object to be sensed and a second surface opposite the first surface, an infrared ray sensor and a visible ray sensor, the infrared ray sensor including a visible ray blocking film contacting the opposite surface, an insulating layer covering and contacting the visible ray blocking film, an active layer disposed on and contacting the insulating layer, a source and drain electrode, each contacting the active layer, the insulating layer and the opposite surface; emitting an infrared ray and a visible ray from the sensing device; disposing the object close to the upper substrate of the sensing device; and sensing the infrared ray or the visible ray reflected by the object through the infrared ray sensor or the visible ray sensor, thereby obtaining information of the object.
 16. The method of claim 15, wherein the information obtained by detecting the infrared ray reflected by the object through the infrared ray sensor is contact information of the object.
 17. The method of claim 15, wherein the information obtained by detecting the visible ray reflected by the object through the visible ray sensor is image information of the object.
 18. The method of claim 15, wherein the obtaining of the information of the object includes: recognizing the contact position of the object by detecting the infrared ray reflected by the object through the infrared ray sensor; and selectively changing the gray level of the visible ray provided to the contact position, thereby recognizing the image information of the object by detecting the visible ray reflected by the object through the visible ray sensor.
 19. The method of claim 18, wherein the selectively changing the gray level of the visible ray is to control the gray level.
 20. The method of claim 15, wherein the sensing device includes: a lower panel; an upper panel facing the lower panel; and a liquid crystal layer disposed between the lower panel and the upper panel, wherein the infrared ray sensor is formed in at least one of the lower panel and the upper panel, and the visible ray sensor is formed in at least one of the lower panel and the upper panel. 